In the SCRUM methodology there are two kinds of actors the pigs = the doer and the chickens the talkers.

These names refer to the following story.

A chicken and a pig discuss and the chicken says:
I have an idea we should open a restaurant.
The pig: why? what do we sell?
The chicken: eggs and bacon
The pig: no way you will be involved and I will be committed.

So in the Scrum methodology only the doers are allowed to talk and give suggestions during a meeting.

The book about SCRUM is worth reading because it is not about programming or development but a about process methodology that works well in combination with XP.
Somebody reported that he used it to steer the organisation of an exhibition.